When I measure it with a thermal scanner the scanner reads 70 degrees celsius.

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70°C !! That's frankly a bit disturbing. It's hotter than a typical hot water pipe or air duct. Sunlight on asphalt on a hot day might get that hot but I don't think vertical concrete ever would. So you have an unknown source of significant energy. That's potentially dangerous. Proceed with caution!

You might check it against another unit to verify if readings persist on a clean dry wall. Not sure what your using, I picked up one of these(INFRARED DT8380) about 5 years ago. They still sell them on amazon.

That's what I was going to ask. You cannot hold your hand in 60°C (140°F) water. A dry surface at 60°C will feel hot but you can certainly get away with brief contact. Concrete at 70°C ought to feel hot to even a glancing touch and intolerable to maintain contact.